Terminal for rheostats



June 7 6.1-1. WHKTTINGHAM TERMINAL FOR RHEOSTATS Filed Jane 18, 1925Patented June 14, 1927..

UNITED STATES PATENT OFFICE.

GEORGE H. WHITTINGHAM, OF BALTIMORE, MARYLAND.

TERMINAL FOR RHEOS'IATS.

Application filed June 18, 1925. Serial No. 88,009.

In my prior applications, Serial Number 725,555, filed July 12, 1924,and Serial Number 17,628, filed March 23, 1925, I have shown in detail arheostat in which the resistance elements consist of fiat metal ribbonswound on edge and supported on fiat supporting members which extendbetween cross bars in a rheostat frame, and also fiat clamping membersadapted to engage the coils, these members constituting terminals forthe coils and connections between the coils. lVhere the rheostats are tobe used in situations where they are not subject to vibration, theconductors from the controllers may be connected directly to the flatterminals mentioned with satisfactory results, but where the rheostatsare used for street car work, for instance, where the rheostats aresubject to much vibration, it is desirable to have a terminal anchoredto the frame of the rheostat for holding the heavy wires and cablesleading to and from the controller.

The purpose of the present invention is to provide a terminal which canbe readily applied to the frame of such a rheostat and which will beanchored so that it cannot be affected by vibration, and which can bereadily connected to the flat terminals or .connectors before mentioned,which are sea cured tothe resistance elements.

In the accompanying drawing, Fig. 1 is a top plan view of a rheostathaving four resistance elements;

Fig. 2 is an end view of the same, from left to right in Fig. 1;

Fig. 3 is a section on the line 33 of Fig. 1, showing the anchoredterminal in central section;

Fig. 4 is a side View of the terminal shown in Fig. 3;

Fig. 5 is a side view of a terminal composed of two parts;

Fig. 6 isan edge view of the terminal shown in Fig. 5; and, i

Fig. 7 is aside view of the rheostat frame on a small scale.

Referring to the drawing, a indicates the frame of a rheostat comprisingside bars 1-'1, connected at their ends by bolts 2, and similar sidebars 33, connected at their ends by bolts 4. The side bars 1 areconnected to the side bars 3 by vertical bars 5, through which the boltsextend. These bars, as shown, are all composed of flat metal strips,

and the bars and bolts constitute a light open" frame. The bolts 4,which constitute e looking cross bars at the ends of the frame. arecovered by tubes of insulating material 6. Flat metal strips 7, coveredby insulating material, support the coils 8, 9, 10, and 11, which arethreaded on to the insulators. The coils, of course, may be connected inany suitable way. In the drawing, the coil 8 has .a flat terminal 12clamped to one end, and

the opposite end of this coil is connected to the coil 9 by similarconnectors 13 and 14 and a flexible conductor 15. The left hand ends ofthe lower coils 9 and 10 are connected together by a flat connector 16,and the right hand end of the lower coil 10 is connected to thecorresponding end of the coil 11 by connectors 17 and 18 and flexibleconductor 19, and the left hand end of the upper coil 11 is providedwith a fiat terminal 20. Thus, as shown in the drawing, the coils areconnected in series, with the terminals 12 and 20, adjacent the uppercross bar 2.

Upon the cross bars 2 and 4 are shown three anchored terminals t, t andt Each terminal, as shown in Figs. 3 and 4, comprises a'flat metal striplonger than the distance between the bars at one end of the frame andprovided near its ends with spaced openings 21 and 22. adapted to fitover the bars 2 and 4 and the insulating tubing thereon. Each terminalhas suitable clamping means 23, at a point between the openings 21 and22, and it also has at one end a head 24 provided with openings 25 and26, adapted to receive the ends of cables or conductors which may besecured within the openings by set screws 27.

The several supporting bars for the resistance units and the severalanchored terminals are insulated from the bar and from one another andspaced apart by suitable tubular spacing devices 28, which may be forcedtoward one another by tightening the nuts shown on the ends of the crossbars. The anchored terminals may be placed at one or both ends of theframe, as desired. In the drawing. three are shown at one end of theframe. It will be seen that when the nuts on the cross bars aretightened, the terminals t, t and 25 will be firmly secured to a pair ofcross bars and therefore they cannot swing about either of the bars orbe laterally displaced by tugging of the cables which connect them tothe controller of a trolley car, for instance. The anchored terminals tand t, as shown in the drawing, are con.-

I nected to the flat end terminals 12 and 20 on the coils 8 and 11 byflexible conductors 29 and 30, respectively, which conductors aresecured to the anchored terminals by the clamping devices 23. Asthenanchored termina s are in fixed relation to the terminals on thecoils, there is no stress applied to the the connecting wires in thedifferent openings and clamping them to the heads.

The anchored terminals may be of metal cast in one piece, as shown inFigs. 3 and 4, or they may be composed of metal stampings as shown inFigs. 5 and 6. In these latter Views, each terminal t is composed of twoflat strips of sheet metal 32, of like form, connected together by thecentral clamping device 23, and also by bolts 33, passing through thehead of the terminal. The head is suitably shaped to form the openings34 and 35, between the parts, for receiving cables or conductors.

What I claim is:

1. In a rheostat, a frame having crossbars at each end, coil supportingmembers supported at their ends by said bars, edge wound resistancecoils on said members, flat clamps fitting on to said coils, a terminalrigidly secured to and insulated from two of said bars at one end of theframe, and a metal connection between said terminal and one of saidclamps.

'2. In a rheostat, a frame having crossbars at each end, coil supportingmembers supported at their ends by said bars, edge wound resistancecoils on said members, flat clamps fitting on to said coils, a terminalrigidly secured to and insulated from two of said bars at one end of theframe, and a flexible metal connection between said terminal and one ofsaid clamps.

3. In a rheostat, a frame having a pair of parallel cross-bars at eachend, coil-supporting members extending between and suported by the barsat opposite ends of the rame, a terminal having spaced openings fittingover two of said bars at one end of the frame, said members and saidterminal being insulated from the bars and from one another, and tubularspacing devices on the bars for spacing the several members and theterminal apart.

In testimony whereof I hereunto affix my signature. 1

GEORGE H. WHITTINGHAM.

